Name:	cmre_AmountsReclassifiedFromNetSettlementsOnInterestRateSwapsQualifyingForHedgeAccountingToPrepaidLeaseRentals
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Total capital lease obligation remaining balance as at the reporting period end, excluding any interest.

No definition available.

Name:	cmre_CapitalLeaseObligationsRemainingBalance
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

Name:	cmre_FinanceLeaseObligationAbstract
Namespace Prefix:	cmre_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The year the capital lease obligations mature.

No definition available.

Name:	cmre_FinanceLeaseObligationMaturity
Namespace Prefix:	cmre_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

Name:	cmre_FinanceLeasedAssetsAbstract
Namespace Prefix:	cmre_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Amount after accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

No definition available.

Name:	cmre_FinanceLeasedAssetsNet
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Interest expense incurred on finance leases during the reporting period and is included in the income statement.

No definition available.

Name:	cmre_InterestExpenseIncurredOnFinanceLeases
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount before depreciation/ amortization of the difference between the fair value of the asset sold and the carrying amount of the asset, when the fair value of the asset sold is more than its carrying amount and the amount of net settlement of interest rate swaps qualifying for cash flow hedge that has been reclassified as prepaid lease rentals. The prepaid lease rental is amortizing over the lease term.

No definition available.

Name:	cmre_PrepaidLeaseRentalsGross
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The per vessel price for the 3 vessels (MSC Azov, MSC Ajaccio and MSC Amalfi), due to the sale and leaseback transaction.

No definition available.

Name:	cmre_VesselsSaleAndLeasebackPrice
Namespace Prefix:	cmre_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The expense charged against earnings for the periodic recognition of capitalized leases. This element may apply to energy companies that lease mineral producing properties and to other enterprises that capitalize property, plant, or equipment obtained through capital leases.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45031-112735

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Name:	us-gaap_AmortizationOfLeasedAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6455314&loc=d3e45014-112735